High-fluidity non-caking dianhydrohexitol pellets

ABSTRACT

Dianhydrohexitol pellets, whose fluidity is preserved even after lengthy storage, include between 90% and 100%, preferably between 95% and 100%, and more preferentially between 97% and 100% of dianhydrohexitols by weight, on a dry weight basis, and have the particularity of not being subject to caking. A process for preparing the dianhydrohexitol pellets is also described.

FIELD OF THE INVENTION

The present invention relates to dianhydrohexitol pellets, the fluidityof which is retained even after long term storage. Thesedianhydrohexitol pellets thus exhibit the distinguishing feature of notbeing subject to caking.

PRIOR ART

Dianhydrohexitols (1,4:3,6-dianhydrohexitols), also known as isohexides,are products of the internal dehydration of hydrogenated C₆ sugars(hexitols), such as sorbitol, mannitol and iditol. In the present patentapplication, the term “dianhydrohexitols” encompasses isosorbide(1,4:3,6-dianhydrosorbitol), isomannide (1,4:3,6-dianhydromannitol),isoidide (1,4:3,6-dianhydroiditol) and the mixtures of at least two ofthese products.

The industrial applications of dianhydrohexitols are currentlyexperiencing vigorous growth, in particular in the pharmaceutical field,in that of chemical synthesis intermediates and that of plastics.

For the majority of these applications, it is generally necessary tohave available compositions which are as pure as possible, in particularhaving a dianhydrohexitol content at least equal to 98.5% by weight,preferably at least equal to 99.5% by weight, of said compositions on adry basis.

Dianhydrohexitols, in particular isosorbide, are highly hygroscopic andchemically rather unstable products and are consequently greatly subjectto caking.

The Applicant Company has in particular observed that the storage ofdianhydrohexitols manufactured according to known processes led, undercertain humidity and temperature conditions, to significant caking andchemical decomposition.

The dianhydrohexitol compositions thus caked during storage raise a goodnumber of problems. This is because the caking not only causes serioushandling difficulties during operations such as the transfer thereof,the unpacking thereof, the milling thereof, the redissolution thereof,and the like, but it also has a major impact on the output of theseoperations.

A number of solutions have been proposed in order to overcome thesedifficulties:

-   -   to add anticaking agents to the dianhydrohexitol composition,    -   to prepare a specific external packaging material such that it        prevents the uptake of water by the composition and consequently        the caking of said composition.

Thus, in the more general field of the polyols, the patent JP No. 74 88183 discloses the addition of esters of organic acids or of acetals asanticaking agents. According to this patent, the addition of 0.005% byweight of butyl cellulose acetate makes it possible for neopentyl glycolnot to exhibit caking for 30 days under a pressure of 0.23 bar after theforming thereof.

Another method for preventing polyols from caking has also beendescribed in the patent FR No. 2 477 902. It has thus been proposed toadd from 0.005% to 0.25% by weight of tertiary amines which comprise atleast two identical organic substituents in order to prevent the cakingof polyols.

However, the addition of anticaking agents is not generally selected byspecialists in the specific field of dianhydrohexitol compositions, inparticular because:

-   -   the introduction of impurities into said compositions may harm        their properties and thus their commercial value,    -   regulatory constraints forbid the use of such additives in some        applications.

With regard to the use of a method for packaging the dianhydrohexitolcompositions, this second technical solution has not to date givenentirely satisfactory results.

Among these packaging methods, the patent application JP 2006-117649discloses the use of a packaging material of film type for packagingisosorbide with the aim of protecting the latter from water absorption,of keeping it in the fluid powder form and of preventing formation ofaggregates. The packaging film is defined as being a multilayer filmbased on plastics and aluminum.

The Applicant Company has itself prepared a packaging based onthermoplastic polymer for packaging dianhydrohexitols. Said packaging,disclosed in the patent application FR No. 2 919 587, is intended forboth solid and liquid dianhydrohexitol compositions. The solid formsconcerned may, for example, be cooled and solidified distillates or maybe crystals, it being possible for all of these products to be providedin particular in the form of a powder or flakes. However, said packaginghas given very good results in terms of prevention of chemicaldecomposition of dianhydrohexitol compositions during storage but hasnot made it possible to lastingly prevent the caking of saidcompositions.

The aim of the present invention is thus to provide dianhydrohexitolcompositions, the fluidity of which is preserved even after storage ofseveral hundred stacked kilograms of product for long periods of time.

Another specific aim of the present invention is also to providedianhydrohexitol compositions which can easily flow, which are easy tometer out by volume and which leave no or virtually no residues in theempty packaging after use.

A specific aim of the present invention is to provide compositions whichform little or no dust.

Another aim of the present invention is to provide compositions whichemploy very small amounts of anticaking agent and which advantageouslydo not employ any of it at all.

Another aim of the present invention is to provide compositions with anextremely high content of dianhydrohexitols, in particular ofisosorbide, i.e. comprising between 90% and 100% by weight, preferablybetween 95% and 100% by weight and more preferably still between 97% and100% by weight on a dry basis of dianhydrohexitols.

Another aim of the present invention is to provide dianhydrohexitolcompositions which can exhibit a relatively high residual moisturecontent, for example of the order of from 0.2% to 0.5% by weight of saidcompositions, and which nevertheless exhibit a low propensity to cake.

Yet another aim of the present invention is to provide dianhydrohexitolcompositions capable of being rapidly dissolved or melted.

SUMMARY OF THE INVENTION

A subject matter of the present invention is dianhydrohexitol pelletscomprising between 90% and 100% by weight, preferably between 95% and100% by weight and more preferably between 97% and 100% by weight on adry basis of the composition of said dianhydrohexitol pellets. Thedianhydrohexitol pellets according to the invention comprise less than2% by weight of anticaking agent, preferably less than 0.5% by weight,more preferably still less than 0.01% by weight and more preferablystill less than 0.001% by weight on a dry basis of the composition ofsaid dianhydrohexitol pellets. Advantageously, the pellets according tothe invention are devoid of any anticaking agent and are neverthelessnot very subject to caking.

Another subject matter of the invention is a process for the preparationof said dianhydrohexitol pellets.

DETAILED DESCRIPTION

A subject matter of the present invention is dianhydrohexitol pelletscomprising between 90% and 100% by weight, preferably between 95% and100% by weight and more preferably between 97% and 100% by weight(dry/dry) of the composition of said dianhydrohexitol pellets. Morepreferably still, the pellets according to the invention exhibit adianhydrohexitol content of greater than or equal to 98.5% by weight,preferably of greater than or equal to 99.5% by weight, (dry/dry) of thecomposition of said dianhydrohexitol pellets. The remainder to 100% byweight on a dry basis of the composition of said dianhydrohexitolpellets can be composed of hexitols, monoanhydrohexitols, stabilizingagents, such as those mentioned in the patent EP 1 446 373, anticakingagents, and various impurities and coproducts, such as those mentionedin the patent EP 1 287 000 (section [0008]) and related to the processfor the production of the dianhydrohexitols, in particular to thedehydration stage of said process.

The pellets according to the invention in addition do not comprise muchanticaking agent or do not comprise anticaking agent and arenevertheless not very subject to caking.

Another subject matter of the invention is a process for the preparationof said dianhydrohexitol pellets.

In the present patent application, the term “pellet” is understood tomean a compact three-dimensional product obtained by “pelleting”. Thus,the term “pellet” comprises the terms tablet, pebble, granule, bar, beadand/or any other shape obtained by “pelleting”. Said pellet can exhibitflat or rounded and concave or convex upper and lower faces. Said pelletcan without distinction be of round, oval, square, rectangular,octagonal, polygonal, and the like, general shape. Preferably, thepellet according to the invention is dome-shaped, that is to say that ithas a flat face and a convex face, the edges between the two faces beingmore or less softened.

In the present patent application, the term “pelleting” is understood tomean a process combining a stage of dropping drops with a stage ofcooling said drop, said process thus making it possible to producepellets with stable and uniform shapes which are substantially devoid ofparticles having a fine particle size. In the present patentapplication, the term “drop” is understood to mean any defined amount ofmolten product. Thus, the pellets according to the invention aresolidified directly from molten dianhydrohexitols, thus eliminatingenergy and equipment costs associated with subsequent stages of millingor crushing or with any other stage of the same type.

The pellets according to the invention can be obtained by employingdifferent types of pelletizers, such as disk pelletizers, beltpelletizers, and the like. In particular, the pelleting according to theinvention can be carried out according to the pelleting processesdescribed in the patent application WO 2009/010673.

Prior to the pelleting process, the dianhydrohexitol composition ismaintained in the molten state in a feed vessel. Dianhydrohexitol “melt”is then referred to. To do this, the dianhydrohexitol(s) is/areadvantageously maintained at a temperature greater than or equal toits/their melting point, in particular, for isosorbide, at a temperaturegreater than or equal to 63±2° C. The dianhydrohexitol composition canresult from a distillation of a crude reaction mixture, from a meltingof a product purified by crystallization in the molten phase or in anaqueous or organic solvent, or from a concentrating to dryness of adianhydrohexitol solution purified according to the patent EP 1 287 000.

Preferably, the melt is introduced into the pelleting unit via a heatedpipeline and a constant-delivery pump. The adjustable pump makes itpossible to feed the pelletizer at the required pressure.

The first stage of the pelleting process consists of the production ofdianhydrohexitol drops from a melt. According to a preferred form of theinvention, the melt arrives at a feed/metering unit where it isconverted into pellets, the particle size and the amount of which aredetermined by the diameter and the number of holes or nozzles selected.It is injected into one or more drop generators, for example by excesspressure, which convert the continuous product flow into uniform dropsof predetermined diameter.

The stage of production of dianhydrohexitol drops is followed by a stageof cooling of said drops. This cooling stage can be carried out by anytype of process well known to a person skilled in the art, for exampleby immersion in a coolant (quenching, cold air, and the like) or bydropping drops onto a moving metal surface cooled by a cooling liquid.Preferentially, this cooling stage is carried out by dropping drops ontoa cooling belt composed of a moving metal belt cooled by a water circuitor by dropping drops onto a horizontal plate cooled by a cooling liquid.The cooling of the drops has to be such that said drops have to reach atemperature lower than the melting point of the dianhydrohexitol(s), inparticular lower than 63±2° C. for isosorbide, so that the shape of saidpellets is definitively stabilized.

The synchronization of the feed/metering unit and of the system forcooling the cooling disks, which takes place during the metering of thedrops of melt, provides for the shaping of the pellets. In addition, theapparatus can be equipped with a closed-circuit cooling system in orderto prevent any contamination of the product by the water vapors or bythe cooling fluid, as well as any contamination of the cooling fluid.

According to a preferred form of the present invention, the pelletizercan be a Rotoform® pelletizer sold by Sandvik. Such a pelletizer iscomposed of a heated stationary cylindrical body (stator) whichcomprises a longitudinal feed groove and around which a rotatingperforated tube is found. When a series of perforations of the tubepasses under the groove of the stator, a small amount of product isreleased and is dropped in the form of drops onto the steel belt, wherethey are cooled and solidified. The peripheral speed of the pelletizeris synchronized with the rate of forward progression of the steel belt.

Prior to the pelleting process, the dianhydrohexitol composition isprepared, no matter the way, for example according to the processdescribed in the patent EP 1 287 000; it can be subjected to variousprocesses of purification, concentration, crystallization, and the like,well known to a person skilled in the art. In particular, thedianhydrohexitols can be subjected to at least one treatment with activecharcoal and/or at least one ion-exchange means. Furthermore, thedianhydrohexitols can be stabilized beforehand according to the teachingof the patent EP 1 446 373.

The dianhydrohexitol pellets according to the invention comprise between90% and 100% by weight, preferably between 95% and 100% by weight andmore preferably between 97% and 100% by weight on a dry basis of thecomposition of said dianhydrohexitol pellets.

Said pellets according to the invention additionally comprise less than2% by weight of anticaking agent, preferably less than 0.5% by weight,more preferably still less than 0.01% by weight and more preferablystill less than 0.001% by weight on a dry basis of the composition ofsaid dianhydrohexitol pellets.

The pellets in accordance with the invention are furthermorecharacterized by their bulk density and their tapped density, and alsoby their tapping, the values being calculated according to the test Adescribed below, using the Stampf Volumeter STAV 2003 device.

Under these conditions, the pellets in accordance with the inventionadvantageously exhibit:

-   -   a bulk density of between 0.80 and 1.00 g/ml, preferably of        between 0.81 and 0.85 g/ml and more preferably still of between        0.82 and 0.84 g/ml,    -   a tapped density of between 0.81 and 1.00 g/ml, preferably of        between 0.82 and 0.86 g/ml and more preferably still of between        0.83 and 0.85 g/ml, and    -   a tapping at most equal to 2%, preferably between 0.5% and 2%        and more preferably still between 0.8% and 1.6%.

The tapped and bulk density and also tapping values of the pellets inaccordance with the invention are determined, according to the test A,using the Stampf Volumeter STAV 2003 device, following the methodrecommended in the directions for use of said Stampf Volumeter. Thus,the test A consists in introducing an amount of product, such that itfills a volume of 250 ml, into a measuring cylinder with a diameter of35 mm and a height of 335 mm. Whatever the product tested, the productis introduced into said measuring cylinder so as to always fill one andthe same volume of 250 ml (volume before tapping). The volume of product(volume after tapping) is subsequently measured after 1250 taps givenfrom the top downward (drop of 3 mm+/−0.2).

The Stampf Volumeter STAV 2003 device thus makes it possible to measure,under standardized and reproducible conditions, the aptitude for tappingof a product by calculating the bulk density, the tapped density and,from these data, the tapping values according to the following formulae:Bulk density=weight of product introduced into the measuringcylinder(g)/250(ml)Tapped density=weight of product introduced into the measuringcylinder(g)/X(ml)with X=volume(ml)occupied by the product after tappingTapping(%)=[(tapped density−bulk density)/bulk density]×100with tapped density=tapped density after a tapping carried out with 1250taps given from the top downward (drop of 3.0±0.2 mm).

The dianhydrohexitol pellets in accordance with the invention can alsobe characterized by their compressibility, evaluated according to thetest B described below.

The compression test B consists in introducing a certain weight ofproduct, quantified in grams, into a hollow brass cylinder with aninternal diameter of 4.8 cm and a height of 8 cm, placed in acrystallizing dish with a diameter of 95 mm. A piston weighing 1.3 kg,fitting exactly into the hollow brass cylinder, is set down on theproduct present in said cylinder. Whatever the product tested, thecylinder always comprises substantially the same volume of product (thefilling height of the cylinder being substantially the same, set at5.9±0.2 cm). Immediately after putting the piston in place on theproduct introduced into the cylinder, the precise height of the whole ofthe product introduced into the cylinder is measured (height beforecompression). The piston/product/cylinder/crystallizing dish assembly issubsequently placed in an aluminum bag (22 cm×41 cm) (Z 183407 bag soldby Aldrich). The bag is immediately closed by sealing using an impulseheat sealer (SZ 380 model sold by Joisten & Kettenbaum GmbH & Co,Bergisch Gladbach, Germany) in order to ensure leaktightness withrespect to the external atmosphere. The samples thus packaged are placedfor 1 week in a ventilated oven, thermostatically controlled at atemperature either of 20° C. or of 40° C. After this period of one week,the bag is opened and the precise height of the whole of the productintroduced into the cylinder is measured (height after compression). Thecompressibility of the product is calculated according to the followingformulae:D _(before)=weight of product introduced into the cylinder(g)/[(π×d ² ×h_(before))/4]with D_(before)=density before compression in g/cm³; d=internal diameterof the cylinder (cm)=4.8 cm; h_(before)=height of the product in thecylinder before compression (cm); π=piD _(after)=weight of product introduced into the measuringcylinder(g)/[(π×d ² ×h _(after))/4]with D_(after)=density after compression in g/cm³; d=internal diameterof the cylinder (cm)=4.8 cm; h_(after)=height of the product in thecylinder after compression (cm)Compressibility(%)=[(D _(after) −D _(before))/D _(before)]×100

The pellets in accordance with the invention advantageously exhibit acompressibility, evaluated at 20° C., of less than 5%, preferably ofless than 3% and more preferably still of less than 2%. Said pellets inaddition advantageously exhibit a compressibility, evaluated at 40° C.,of less than 5%, preferably of less than 4.5%.

The pellets in accordance with the invention can also be characterizedby their low aptitude for caking. The aptitude for caking is evaluatedin particular using the test C described below.

The caking test C, which is similar to that described in the first claimof the patent application EP 1 787 993 A1, consists in introducing 70 gof product into a glass flask with a height of 12 cm and an internaldiameter of 6 cm. Said flask, thus filled, is hermetically closed andplaced, for 2 or 4 weeks, in a ventilated oven, the internal temperatureof which is set at 20° C. or at 40° C. After 2 or 4 weeks, the flask isremoved from the oven, opened and then inverted by an angle of 90° andthen of 180° along a horizontal axis. A score is assigned to the productaccording to its form of flow:

-   -   a score of 0 is assigned to the product if it flows completely        and immediately when the flask is placed at 90°;    -   a score of 1 is assigned to the product if it flows completely        within a maximum period of time of 1 minute when the flask is        placed at 180°;    -   a score of 2 is assigned to the product if it        -   does not flow, even after the flask has been placed at 180°            for more than one minute, but        -   flows after a weight of 300 g has been dropped, from a            height of 10 cm, onto the base of the flask placed at 180°;    -   a score of 3 is assigned to the product if it does not flow,        even after the flask has been placed at 180° for more than one        minute and after a weight of 300 g has been dropped, from a        height of 10 cm, onto the base of the flask placed at 180°.

The pellets in accordance with the invention advantageously exhibit ascore of 1 in the caking test C carried out at 20° C. for 2 or 4 weeksand a score of 1 or 2 in the caking test C carried out at 40° C. for 2or 4 weeks.

The pellets in accordance with the invention can also exhibit theadvantage of being chemically stable during storage. According to theinvention, the chemical stability is evaluated, according to the test D,by pHmetry (confirmation of the stability of the pH).

The stability test D consists in evaluating, in a first step, the pH ofa sample of product dissolved, at 40% by weight of dry matter, inosmosed water. Subsequently, 50 g of another sample of this same productare introduced into a glass flask and then said flask is hermeticallyclosed and placed in a ventilated oven, thermostatically controlled at atemperature of 50° C. Several flasks, filled with the same product, areplaced in the oven. After a predetermined period, all of the sample ofproduct is extracted from the flasks and dissolved, at 40% by weight ofdry matter, in osmosed water. The pH measurement is carried out on apHmeter of Radiometer Analytical PHM 220 brand equipped with a combinedAg/AgCl wire electrode of Mettler Toledo brand, calibrated beforehandusing pH 7 and 4 buffer solutions.

The pellets in accordance with the invention advantageously exhibit apH, evaluated according to the test D, of greater than or equal to 7,preferably of between 7.0 and 8.5, after 6 months of storage in a glassflask placed in a ventilated oven thermostatically controlled at atemperature of 50° C. This pH, of greater than or equal to 7, shows anabsence of generation of acidity (synonymous with decomposition of thedianhydrohexitols with formation of formic acid) and shows an excellentstability of the dianhydrohexitol pellets in accordance with theinvention.

The pellets in accordance with the invention also exhibit the advantageof rapidly dissolving, their dissolution time being the same as those ofthe other shaping outcomes known to date. Thus, the pellets inaccordance with the invention can be characterized by a dissolution timein water of less than or equal to:

-   -   12 minutes, preferably 10 minutes, when said pellets are        dissolved at 20° C. in a final dry matter in the solution of        50%; and    -   6 minutes, preferably 5 minutes, when said pellets are dissolved        at 40° C. in a final dry matter in the solution of 50%.

According to the invention, the dissolution is evaluated according tothe test E. Said dissolution test E consists in introducing a testportion of 100 g of product into a 250 ml beaker containing 100 ml ofdistilled water preheated to 20° C.±2° C. or to 40° C.±2° C. Theproduct/distilled water combination is stirred using a magnetic bar(reference No. ECN 442-4510/VWR). The time which has passed between theintroduction of the test portion into the beaker and the completedissolution of the test portion in the water is then determined. Theexperiment is carried out 3 times for each sample. According to thepresent invention, the dissolution time of the sample corresponds to themean of the results of the three experiments.

The dianhydrohexitol pellets in accordance with the invention alsoexhibit the advantage of being able to rapidly melt, their melting timebeing of the same order of magnitude as those of the other shapingoutcomes known to date. Thus, the pellets in accordance with theinvention can be characterized by a melting time of less than 25minutes, preferably 22 minutes, when said pellets are heated to 80° C.

According to the invention, the melting time is evaluated according tothe test F. Said melting test F consists in introducing a test portionof 100 g of product into a 250 ml beaker heated beforehand to 80° C.±2°C. The test portion is stirred using a magnetic bar (reference No. ECN442-4510/VWR). The time which has passed between the introduction of thetest portion into the beaker and the complete melting of the testportion is then determined. The experiment is carried out 3 times foreach sample. According to the present invention, the melting time of thesample corresponds to the mean of the results of the three experiments.

The pellets in accordance with the invention are also advantageouslycharacterized in that at least 90% by weight, preferably 95% by weightand more preferably still 94% by weight of the pellets exhibit aparticle size on sieves of greater than or equal to 2000 μm, preferablyof between 2000 μm and 20 000 μm. According to the invention, theparticle size on sieves of the pellets is evaluated according to thetest G described below.

Said test G is carried out using the VS 1000 laboratory siever sold byRetsch, according to the method recommended in the directions for use ofsaid siever. According to the test G, said siever is equipped with asieving tower composed of 7 sieves with a diameter of 20 cm, the meshsizes of which are respectively 20 000 μm, 5000 μm, 2000 μm, 1400 μm,1000 μm, 500 μm and 355 μm (the sieves are placed from the top downward,from the widest mesh size down to the narrowest mesh size). Briefly, thetest G consists in introducing a test portion of 200 g of product at thetop of the sieving tower and in starting the siever in continuous mode,at a vibrational amplitude of 50%, for 10 minutes. After sieving for 10minutes, the siever is halted and the amount of product retained on eachof the sieves is quantified by weighing.

The pellets according to the invention preferably exhibit a moisturecontent, evaluated by the Karl Fischer method, of less than 1% byweight, preferably of less than 0.5% by weight and more preferably stillof less than 0.3% by weight of the dianhydrohexitol composition of saidpellets.

The pellets according to the invention or capable of being obtained bythe process according to the invention make it possible to producespecific compositions suited to fields as diversified as nutraceuticals,pharmaceuticals, cosmetics, chemistry, construction materials,paper/board or polymers. Thus, the present invention additionallyrelates to the use of the pellets according to the invention or obtainedby the process according to the invention in the manufacture ofderivatives of dianhydrohexitols and of polymers comprising at least onedianhydrohexitol or one derivative of the latter.

An even better understanding of the invention will be obtained with thehelp of the following examples, which are not meant to be limiting andreport only certain embodiments and certain properties which areadvantageous of the pellets in accordance with the invention.

EXAMPLES

In the examples 2 to 6 below:

-   -   the term “pellets V1, V2 and V3” is understood to mean        isosorbide pellets in accordance with the invention with a        thickness of 2 mm, the greatest length (diameter) of which are        respectively 4 mm, 5 mm and 7 mm, obtained according to the        pelleting process described in detail in example 1;    -   the term “flakes” is understood to mean isosorbide flakes        obtained by crystallization on a cooled rotating cylinder,        feeding being carried out by dipping in a vat containing the        molten isosorbide;    -   the term “bulk crystals” is understood to mean isosorbide        crystals obtained by crystallization from a solvent of alcohol        type, followed by filtering off and drying under vacuum in a        filter-dryer of said crystals obtained;    -   the term “355-1400 crystals” is understood to mean crystals        resulting from a 355-1400 μm particle size fraction produced        from the “bulk crystals” described above. The particle size        fraction is produced using the VS 1000 laboratory siever sold by        Retsch, the method recommended in the directions for use of said        siever being followed. Said siever is equipped, for producing        the fraction, with a sieving tower composed of 2 sieves with a        diameter of 20 cm, the mesh sizes of which are respectively 355        μm and 1400 μm (the sieves are placed from the top downward,        from the widest mesh size down to the narrowest mesh size).

Example 1 Preparation of Isosorbide Pellets in Accordance with theInvention

Isosorbide with a purity of 99.8% and comprising 0.2% of water isintroduced in the form of flakes into a heated and stirred cylindricalvessel. When the product has been completely melted, it is maintained ata temperature of 65° C.±2° C. and pelleting is carried out using theRotoform® 3000 pelletizer sold by Sandvik.

Operating Parameters:

-   -   Feed temperature: 65° C.±2° C.    -   Speed of the belt: 9.5 m/min    -   Speed of the Rotoform®: 11 m/min    -   Belt width: 600 mm    -   Cold belt length: 7.5 m    -   Total length of the belt: 10 m    -   Cooling water for the belt: filtered decarbonated water at        20° C. with a flow rate of 5 m³/h    -   Pellet production rate: 360 kg/h

The choice of the perforation diameter of the feed tube makes itpossible to obtain pellets with different diameters.

The following pellets are obtained by applying the operating parametersdescribed above with feed tubes with appropriate perforation diameters:

-   -   pellets V1: diameter 4 mm and thickness 2 mm    -   pellets V2: diameter 5 mm and thickness 2 mm    -   pellets V3: diameter 7 mm and thickness 2 mm

Likewise, the same procedure as above is followed, taking as startingmaterial isosorbide with a purity of 97% in the form of flakes. Thefollowing pellets are thus obtained by applying the operating parametersdescribed above with feed tubes with appropriate perforation diameters:

-   -   pellets V4: diameter 4 mm and thickness 2 mm    -   pellets V5: diameter 5 mm and thickness 2 mm    -   pellets V6: diameter 7 mm and thickness 2 mm

Example 2 Comparison of the Behavior of the Isosorbide Compositions inAccordance with the Invention and of the Isosorbide Compositions in theForm of Flakes or Crystals During Tapping and Compression Tests

2.1 Tapping Test

The bulk density, the tapped density and the tapping of differentisosorbide shaping outcomes are evaluated according to the test A. Theseparameters are in particular compared for isosorbide pellets withdifferent diameters (V1, V2 and V3) in accordance with the invention,isosorbide flakes and isosorbide crystals (bulk crystals or crystalsresulting from a 355-1400 μm fraction).

The results of this evaluation are presented in table 1.

TABLE 1 Results of the tapping tests carried out on different isosorbideshaping outcomes Volume Density Density after before after tappingWeight tapping tapping Tapping Form (ml) (g) (g/ml) (g/ml) (%) Pellets248 207.7 0.83 0.84 0.8 V1 Pellets 246 208.9 0.84 0.85 1.6 V2 Pellets248 205.3 0.82 0.83 0.9 V3 Flakes 239 185.9 0.74 0.78 4.6 Bulk 230 168.10.67 0.73 8.8 crystals Crystals 230 166.7 0.67 0.73 8.7 (355-1400 μm)

The pellets in accordance with the invention exhibit a bulk density anda tapped density which are far superior to those of the productsexisting on the market (flakes and crystals). In addition, said pelletsexhibit a tapping which is very markedly lower than that of the flakesand crystals.

In comparison with the other forms of shaping outcome, the isosorbidepellets are thus more suitable for being transported in large volumesince they settle down less and are thus less susceptible to caking andsince they exhibit, despite this, a greater density, both tapped andbulk.

2.2 Compression Test

The density before compression (D_(before)), the density aftercompression (D_(after)) and the compressibility of different isosorbideshaping outcomes are evaluated according to the test B. These parametersare in particular compared for isosorbide pellets V1, V2 and V3 inaccordance with the invention, isosorbide flakes and isosorbide crystals(bulk crystals or crystals resulting from a 355-1400 μm fraction).

The results of this evaluation are presented in table 2.

TABLE 2 Results of the compression tests carried out on differentisosorbide shaping outcomes Oven thermostatically controlled at 20° C.:Height Height Weight Compress- before after before D_(before) D_(after)ibility Form (cm) (cm) (g) (g/cm³) (g/cm³) (%) Pellets V1 5.8 5.7 90.50.86 0.88 2 Pellets V2 5.7 5.7 90.5 0.88 0.88 0 Pellets V3 5.9 5.9 91.10.85 0.85 0 Flakes 6.1 5.7 83.6 0.76 0.81 7 Bulk 5.9 5.3 78.4 0.73 0.8211 crystals Crystals, 5.9 5.3 78.6 0.74 0.82 11 355-1400 Oventhermostatically controlled at 40° C.: Height Height Weight (cm) (cm)(g) Compress- before after before D_(before) D_(after) ibility Formtapping tapping tapping (g/cm³) (g/cm³) (%) Pellets V1 5.8 5.6 90.6 0.860.89 4 Pellets V2 5.7 5.5 90.6 0.88 0.91 4 Pellets V3 6.0 5.8 92.4 0.850.88 4 Flakes 5.9 5.5 83.7 0.78 0.84 7 Bulk 5.8 5.1 77.4 0.74 0.84 14crystals Crystals, 5.8 5.1 78.5 0.75 0.85 14 355-1400

The pellets in accordance with the invention exhibit a density beforeand after compression (respectively D_(before) and D_(after)) which arefar superior to those of the products existing on the market (flakes andcrystals). In addition, said pellets exhibit a compressibility which ismarkedly lower than that of the flakes and crystals.

In comparison with the other forms of shaping outcome, the isosorbidepellets are thus more suited to being transported in large volume sincethey are less compressible.

Example 3 Comparison of the Behavior of the Isosorbide Compositions inAccordance with the Invention and of the Isosorbide Compositions in theForm of Flakes or Crystals During Caking Tests

The aptitude for caking of isosorbide pellets in accordance with theinvention, of isosorbide flakes and of isosorbide crystals was evaluatedaccording to the caking test C as described above.

The results of this evaluation are presented in table 3.

TABLE 3 Results of the caking tests in a ventilated oventhermostatically controlled at 20° C. or at 40° C. carried out ondifferent isosorbide shaping outcomes Crystals Time Pellets 355- (weeks)V1 V2 V3 Bulk 1400 μm Flakes Oven thermostatically controlled at 20° C.:2 1 1 1 2 2 1 4 1 1 1 2 2 1 Oven thermostatically controlled at 40° C.:2 2 1 1 2 2 2 4 2 2 2 3 3 2Scores: 0=product flowing completely and immediately when the flask isplaced at 90°; 1=product flowing completely within a maximum period oftime of 1 minute when the flask is placed at 180°; 2=product notflowing, even after the flask has been placed at 180° for more than oneminute, but flowing after a weight of 300 g has been dropped, from aheight of 10 cm, onto the base of the flask placed at 180°; 3=productnot flowing, even after the flask has been placed at 180° for more thanone minute and after a weight of 300 g has been dropped, from a heightof 10 cm, onto the base of the flask placed at 180°.

The isosorbide pellets in accordance with the invention exhibit a scoreof 1 in the caking test C carried out at 20° C. for 2 or 4 weeks and ascore of 1 or 2 in the caking test C carried out at 40° C. for 2 or 4weeks.

Example 4 Analysis of the Chemical Stability of Isosorbide Pellets inAccordance with the Invention

The stability on storage of pellets obtained according to example 1 wasevaluated according to the test D as described above.

The results of this evaluation are presented in table 4.

TABLE 4 Results of the stability tests D carried out on the pellets inaccordance with the invention Storage time Pellets V1 Pellets V2 PelletsV3 0 day 7.6 7.6 7.6 15 days 7.9 7.8 8.0 1 month 8.0 7.6 8.0 2 months8.1 7.8 7.9 3 months 8.0 7.6 8.1 4 months 7.9 7.4 8.0 6 months 8.1 7.88.1

The pH values of the different pellets V1, V2 and V3 remain stable, evenafter storing at 50° C. for 6 months, which shows an absence ofgeneration of acidity (synonymous with decomposition of the isosorbidewith formation of formic acid) and thus an excellent stability of theisosorbide pellets in accordance with the invention.

Example 5 Evaluation of the Dissolution and Melting Times of IsosorbidePellets in Accordance with the Invention and of the IsosorbideCompositions in the Form of Flakes or Crystals

The dissolution time and the melting time of different isosorbideshaping outcomes were evaluated according to the tests E and Frespectively.

The results of this evaluation are presented in tables 5 and 6respectively.

TABLE 5 Results of the dissolution tests E carried out on differentisosorbide shaping outcomes Dissolution time Shaping in water (min)outcome (100 g) 20° C. 40° C. Flakes 5.7 4.1 Bulk crystals 8.9 3.6Pellets V1 6.6 3.4 Pellets V2 7.8 3.6 Pellets V3 9.9 4.9

TABLE 6 Results of the melting tests F carried out on differentisosorbide shaping outcomes Shaping outcome Melting time (min) Flakes15.9 Bulk crystals 17.8 Pellets V1 16.2 Pellets V2 20.4 Pellets V3 22.8

The isosorbide pellets in accordance with the invention exhibit adissolution time which is substantially the same as those of the othershaping outcomes known to date.

In addition, said pellets exhibit a melting time of the same order ofmagnitude as those of the other shaping outcomes known to date.

Example 6 Particle Size Analysis of the Isosorbide Compositions inAccordance with the Invention and of the Isosorbide Compositions in theForm of Flakes or Crystals

The particle size on sieves of different isosorbide shaping outcomes wasevaluated according to the test G. The results of this evaluation arepresented in table 7.

TABLE 7 Particle size according to the test G carried out on differentisosorbide shaping outcomes (% of oversize by weight) Particle size onsieves (μm) 5000 2000 1400 1000 500 355 Shaping to to to to to tooutcome >20 000 20 000 5000 2000 1400 1000 500 <355 Pellets V1 0 51.246.2 1.4 1.2 0.1 0 0 Pellets V2 0 64.0 31.9 2.5 1.4 0.3 0 0 Pellets V3 063.0 31.1 3.8 1.1 0.8 0.2 0 Flakes 0 20.3 52.1 14.6 10.5 2.6 0 0 Bulk 00.9 6.2 9.1 71.2 12.6 0 0 crystals Crystals, 0 0.1 0.3 8.4 87.7 3.3 0.20 355-1400 μm

The isosorbide pellets in accordance with the invention are alsocharacterized in that at least 90% by weight, preferably 94% by weight,of the pellets exhibit a particle size on sieves of greater than 2000μm, preferably of between 2000 μm and 20 000 μm.

The invention claimed is:
 1. A composition of high-fluidity andnon-caking dianhydrohexitol pellets comprising between 90% and 100% byweight of dianhydrohexitols on a dry basis, wherein at least 90% byweight of said pellets exhibit a particle size on sieves of greater thanor equal to 2000 μm and wherein said pellets are selected from the groupconsisting of tablets, pebbles, granules, bars, beads, other shapesobtained by pelleting, and mixtures thereof.
 2. The composition ofdianhydrohexitol pellets as claimed in claim 1, wherein said pellets areof round, oval, square, rectangular, octagonal or polygonal shape. 3.The composition of dianhydrohexitol pellets as claimed in claim 1,wherein said pellets are dome-shaped.
 4. The composition ofdianhydrohexitol pellets as claimed in claim 1, comprising less than 2%by weight of anticaking agent on a dry basis.
 5. The composition ofdianhydrohexitol pellets as claimed in claim 1, wherein saiddianhydrohexitols are selected from the group consisting of isosorbide,isomannide, isoidide and the mixtures thereof.
 6. The composition ofdianhydrohexitol pellets as claimed in claim 1, said dianhydrohexitolpellets exhibiting: a bulk density of between 0.80 and 1.00 g/ml, atapped density, evaluated according to a test A, of between 0.81 and1.00 g/ml.
 7. The composition of dianhydrohexitol pellets as claimed inclaim 1, said dianhydrohexitol pellets exhibiting a tapping, evaluatedaccording to the test A, at most equal to 2%.
 8. The composition ofdianhydrohexitol pellets as claimed in claim 1, said dianhydrohexitolpellets exhibiting a compressibility, evaluated according to a test Bcarried out at 20° C., of less than 5%.
 9. The composition ofdianhydrohexitol pellets as claimed in claim 1, said dianhydrohexitolpellets exhibiting a score of 1 in a caking test C carried out at 20° C.for 2 or 4 weeks and a score of 1 or 2 in the caking test C carried outat 40° C. for 2 or 4 weeks.
 10. The composition of dianhydrohexitolpellets as claimed in claim 1, said dianhydrohexitol pellets exhibitinga pH of greater than or equal to 7 after 6 months of storage in aventilated oven thermostatically controlled at a temperature of 50° C.11. The composition of dianhydrohexitol pellets as claimed in claim 1,wherein at least 95% by weight of the pellets exhibit a particle size onsieves of greater than or equal to 2000 μm.
 12. The composition ofdianhydrohexitol pellets as claimed in claim 1, said dianhydrohexitolpellets exhibiting a moisture content of less than 1% by weight.
 13. Thecomposition of dianhydrohexitol pellets as claimed in claim 1, saiddianhydrohexitol pellets exhibiting a flat face and a convex face.